This invention relates to assemblies for supporting electrical circuit boards within tubes, and is concerned more particularly, but not exclusively, with assemblies for supporting circuit boards within measurement probes to be accommodated down-hole in a borehole such that the circuit boards are substantially resistant to mechanical vibration and shock.
In the surveying of boreholes various measurements are taken down-hole and are processed prior to being transmitted to the surface, for example by means of a mud-pulse signalling transmitter. The appropriate measuring instrumentation and processing circuitry is mounted within a drill collar incorporated in the drill string in the vicinity of the drill bit. More particularly the circuit boards accommodating the measurement and processing circuitry are supported within an elongate tube which is in turn mounted within a sleeve by means of a pivotal coupling at one end to allow limited pivotal movement of the probe within the speeve. The sleeve is then itself mounted within the drill collar with the interposition of a suitable damping medium between the outside of the sleeve and inside wall of the drill collar.
It is an object of the invention to provide an assembly for supporting an electrical circuit within a tube which is suitable for use in such a measurement probe.